Reproductive biology of the greater bandicoot rat Bandicota indica (Rodentia: Muridae) in the rice fields of southern Thailand

Abstract

This study investigated some aspects of the reproductive biology of male and female greater bandicoot rats, Bandicota indica, in southern Thailand from September 2004 to September 2006. In females, body, uterine and preputial gland weights, occurrences of pregnancies and placental scars, and in males, testicular weights and histology, and sizes of accessory sex glands, were recorded. Pregnancies occurred predominantly, but not exclusively, in the wet season, with a higher incidence pregnancies in the second, than in the first, dry season. Uterine and preputial gland weights tended to be lower in the first, but not the second dry season, with placental scars occurring at all times of year. Males tended to have heavier testes in the wet season but some seminiferous tubules contained sperm even in the dry season. Seminal vesicles, but not prostates and preputial glands, tended to be heavier in animals in the wet season. We conclude that the greater bandicoot rat in southern Thailand shows maximal reproductive activity in the wet season with some reproductive activity, albeit variable from year to year, occurring in the dry season depending upon environmental conditions. This study has also shown that females, as well as males, have large preputial glands, and that males invariably have small testes regardless of the time of year. These observations suggest a similar timing of reproduction, but a different breeding biology and perhaps social organisation, from that of the sympatric ricefield rat, Rattus argentiventer

Co‐evolution of gametes of the Greater Bandicoot Rat, Bandicota indica – a murine rodent from South‐East Asia

“…Although it has recently been suggested that the reason for the highly divergent sperm, and its absence of an apical hook, of B. indica may be due to depressed levels of intermale sperm competition since this species has a relatively small testis mass (Thitipramote et al 2009(Thitipramote et al , 2011, the current findings point to a co-evolution of the sperm and egg coats that may relate to divergent processes of sperm-egg interaction at the time of fertilisation. Clearly, a study on the events of fertilisation in the Greater Bandicoot Rat is now required to test this hypothesis.…”

“…; Thitipramote et al . , ). These latter features suggest that the sperm of the Greater Bandicoot Rat, as well as that of its sister species B. savilei , show, in some regards, convergence to the sperm of the distantly related Naked Mole Rat, Heterocephalus glaber (Van der Horst et al .…”

“…Furthermore, in B. indica, the length of the sperm tail is highly variable and, in addition, most have a large cytoplasmic droplet around the neck and postacrosomal region of the sperm head. Also, the principal piece lacks a well-developed fibrous sheath and all of the outer dense fibres are modest and uniform in shape and size (Breed 1998;Breed et al 2007;Thitipramote et al 2009Thitipramote et al , 2011. These latter features suggest that the sperm of the Greater Bandicoot Rat, as well as that of its sister species B. savilei, show, in some regards, convergence to the sperm of the distantly related Naked Mole Rat, Heterocephalus glaber (Van der Horst et al…”

Variation in sperm morphology of a murine rodent from South-East Asia: the Greater Bandicoot Rat, Bandicota indica

“…However, whether this observed variability is because of the obtaining of the sperm samples from individuals that were optimally reproductive active, is not known. A recent study of B. indica collected in the wild over a 2‐year period has shown that these animals reproduce during the rainy season, with some reproductive activity extending into the following dry period for a variable length of time (Thitipramote et al. 2009).…”

Rodent-borne health risks in farming systems

“…An early report from Bombay and Calcutta (1966) showed that B. bengalensis increased in population size enormously and displaced the R. rattus in urban areas (Seal & Banerji, 1966). One of the underlying mechanisms was the high reproductive capacity of B. bengalensis (Parrack & Thomas, 1970;Smiet, Fulk, & Lathiya, 1980;Thitipramote, Suwanjarat, & Breed, 2009), and the aggressive behaviour that dominant males exhibit (Parrack & Thomas, 1970;Smiet et al, 1980). Other research from India reported B. bengalensis to be the most aggressive field rodent (Mann, 1973) and that the females confine most of their time to hoarding food and are less active than males (Parrack & Thomas, 1970).…”